This invention relates to a method of preparing products comprising mineral fibres such as rock wool fibres, slag wool fibres and glass fibres, and a binder including inorganic binder such as cement, gypsum, fusible glasses and metals and organic thermoplastic and thermosetting binders. British patent specification No. 1,267,756 discloses a composition consisting of an intimate mixture of a hydraulic binder, such a cement and fibres, which composition will set to a solid product on the addition of water.
In order to obtain a fibre-reinforced product having physical properties superior to those of products containing no fibres, each fibre should be in intimate contact with and completely surrounded by the binder. Consequently, the fibres should be separated from one another and should be uniformly distributed in the binder used.
However, the prior art attempts to obtain a uniform mixture of fibres and binder, such as cement, have proved unsuccessful, because the fibres tend to form fibre lumps during the mixing operation.
The object of the invention is to provide a fibre-reinforced product in which the fibres are uniformly distributed.
Another object of the invention is to provide a product which does not deteriorate as a result of chemical attack of the fibres.
A further object of the invention is to provide a product containing a high proportion of fibres.
A still further object of the invention is to provide a product in which a sufficient adhesion between the binder and the fibres is obtained.
These objects are achieved by the method of the invention, which method comprises the steps of admixing a noncured binder with mineral fibres which have been subjected to a heat treatment at a temperature of between 550.degree. and 900.degree. C., and in allowing the binder to cure.